FWIW, the data I have on a Wickes 410-169 260W twin automatic shower
pump gives 9L/min @ 1.3Bar. It is always possible to restrict the flow by
adding a restrictor washer into the output side of the pump, this will
reduce the pressure at the shower under flow conditions. The max pressure
for this unit was 1.5Bar at 0L/m dropping to 1Bar @ 20L/m. Hope this helps
Regards
Capitol